An antenna includes a transmission line transmitting signals of a radio frequency module, a radiating part for electromagnetic radiation, and a sub-radiation pattern part that can be regarded as an effective parasitic element having controllable impedance matching and radiation pattern.
Since a helical antenna can be miniaturized for a specific frequency band, and has a high efficiency, it is widely used for miniature wireless apparatuses. However, to use a helical antenna having a shape similar to that of a spring, a space for mounting the antenna must be secured inside a product, and a separate assembling process is required.
Also, since there is a possibility that the shape of the antenna is modified or the performance of the antenna changes depending on an outside environment, deviation in the performance of the antenna may be generated during the separate assembling process of the antenna.